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Class 8 Science - Chemical Effects of Electric Current CBSE Worksheets

Q1: Which effect of electric current is utilized for detecting the flow of current through a solution when a compass is used?

Q2: What is meant by the chemical effect of electric current? Give an example.

Why is electroplating useful?

Q3: A beaker contains an acidified copper sulphate solution. A copper plate and a carbon rod are kept in this copper sulphate solution. The copper plate is connected to the positive terminal of a battery whereas the carbon rod is connected to the negative terminal of the battery. What happens when electric current is passed through copper sulphate solution?

Q4: Name two metals which are usually electroplated on cheaper metals for making jewelry (or ornaments).

Q5: Why the bulb glows when the electric current passes through it?

Q6: Tap water conducts electricity whereas distilled water does not. Give reason.

Q7:  The process that you saw in Activity 14.7 is used for purification of copper. A thin plate of pure copper and a thick rod of impure copper are used as electrodes. Copper from impure rod is sought to be transferred to the thin copper plate. Which electrode should be attached to the positive terminal of battery and why?

Q8: Does pure water conduct electricity? If not, what can we do to make it conducting?

Q9:  In case of a fire, before the firemen use the water hoses, they shut off the main electrical supply for the area. Explain why they do this.

Q10: What happens when electric current is passed through acidified water?

Q11: A child staying in a coastal region tests the drinking water and also the seawater with his tester. He finds that the compass needle deflects more in the case of seawater. Can you explain the reason?

Q12: What is the advantage of using LED in testing the electrical conductivity of liquids?

Q13: For electroplating copper on an iron object, which terminal of the battery (positive or negative) is connected to the iron object?

Q14: Is it safe for the electrician to carry out electrical repairs outdoors during heavy downpour? Explain.

Q15: Which is the polluting waste generated by electroplating factories?


You can find Worksheets Solutions here: Worksheet Solutions: Chemical Effects of Electric Current

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FAQs on Class 8 Science - Chemical Effects of Electric Current CBSE Worksheets

1. What are the chemical effects of electric current?
Ans. The chemical effects of electric current refer to the changes that occur in a substance when an electric current passes through it. These effects include the decomposition of electrolytes, the formation of new substances, and the deposition of metals on electrodes.
2. How does an electric current cause electrolysis?
Ans. When an electric current is passed through an electrolyte, it causes the ions in the electrolyte to move towards the electrodes. At the positive electrode (anode), negatively charged ions (anions) lose electrons and get oxidized, while at the negative electrode (cathode), positively charged ions (cations) gain electrons and get reduced. This leads to the process of electrolysis.
3. What is electroplating?
Ans. Electroplating is a process in which a thin layer of metal is deposited onto the surface of an object using electric current. It is done by immersing the object (to be plated) and a metal electrode (to be deposited) into an electrolyte solution and passing a current through them. This causes the metal ions from the electrolyte to get reduced and form a layer on the object.
4. How is electroplating useful in everyday life?
Ans. Electroplating has various applications in everyday life. It is used to improve the appearance of objects by giving them a shiny and attractive surface. For example, jewelry, silverware, and car parts are often electroplated. It is also used to prevent corrosion by coating objects with a layer of a less reactive metal. Additionally, electroplating is used in electrorefining processes to purify metals.
5. What is the role of electrodes in the chemical effects of electric current?
Ans. Electrodes play a crucial role in the chemical effects of electric current. They are the conductors that allow the electric current to enter and leave the electrolyte. The positive electrode (anode) attracts negatively charged ions (anions) and undergoes oxidation, while the negative electrode (cathode) attracts positively charged ions (cations) and undergoes reduction. The choice of electrodes can also determine the type of reaction and the substances formed during the chemical effects of electric current.
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